Famed investor and ARK Invest CEO Cathie Wood's Ark Innovation ETF (ARKK -3.00%) seeks to own companies that have the potential to change how the world works by introducing disruptive products or services. The strategy has proven its worth by absolutely crushing the market over the past one-, three-, and five-year periods. 

Two such examples in her popular exchange-traded fund are Roku (ROKU -3.31%), the streaming entertainment company, and Square (SQ -1.59%), the digital payments service. Besides being disruptors in their respective industries, both businesses have demonstrated an intense focus on taking care of their various users. 

And it's a big reason why they have so far been runaway successes. Let's take a closer look:

Two business people shaking hands.

Image source: Getty Images.

TV operating system of the future 

Roku is the third-largest holding in the Ark Innovation ETF, accounting for 5.3% of the portfolio as of Aug. 30. Shares of the popular streaming platform have skyrocketed over 1,400% since going public in September 2017.  

Roku allows viewers, content companies, and advertisers to all come together in a way that wasn't possible before. Consumers can use Roku's media players and branded TVs to see a wide range of streaming services all in one place. And those streaming services, like Netflix and AT&T's HBO Max, want to utilize Roku's distribution capabilities to reach a wider audience. Furthermore, this all provides immense value to organizations looking to shift ad dollars from traditional TV to connected TV, and Roku is constantly looking for ways to offer new tools for companies to target viewers. 

It's no wonder that in the most recent quarter, Roku's revenue jumped 81% year over year, active accounts exceeded 55 million, and 17.4 billion hours of content was streamed on its platform. 

Leveling the economic playing field 

Now, let's take a closer look at Square. As of Aug. 30, the fintech innovator made up just under 4% of the Ark Innovation ETF. And over the past five years, the company has seen its stock skyrocket more than twentyfold.  

Square's sellers need a one-stop shop in order to start, run, and grow their businesses. Before Square, this was a complex and painful process that required the use of multiple vendors, adding to merchants' frustrations. This segment produced gross profit of $585 million in the second quarter, an 85% increase from the prior-year quarter.  

The Cash App, which currently has 40 million monthly active users, offers consumers an easy-to-use financial services tool that they can utilize daily. In addition to sending and receiving money to and from others, you can buy Bitcoin, invest in stocks, and request a debit card to use anywhere Visa is accepted. In the second quarter, gross profit per Cash App customer was 150% higher than two years ago. 

And Square's ability to continue incorporating value-added services for both sellers and Cash App customers only bolsters its importance in their lives. 

The investor takeaway 

The purpose of any enterprise is obviously to cater to its user base, but Roku and Square excel more than other companies because they understand the significance of addressing different users' various and evolving needs. These businesses want to build a lifelong relationship with the people who use their products as opposed to just a one-off transaction. And that approach is why they've been so successful. 

It should then come as no surprise that Wood has placed large bets on Roku's and Square's stocks. For the individual investor, think about how the company you're interested in takes care of its user base. If management has an unwavering commitment to them, it could be a winning stock.